1. Field of the Invention
The present invention relates to an audio disc in which an audio signal of text information indicating a music name or the like is recorded, an encoding apparatus in which the audio signal of the text information is recorded in the audio disc, and a disc reproducing apparatus in which the audio signal recorded in the audio disc is reproduced to display the text information indicated by the audio signal.
2. Description of the Related Art
2.1. Previously Proposed Art
A conventional compact disc (CD) has been known as a conventional audio signal reproducing optical disc. Also, a digital video disc (DVD) has been recently known as an optical disc having a packing density higher than the CD.
Also, another conventional compact disc (CD) has been known as a storage medium in which text information (or character information) indicating a music name of each music source is recorded as an audio signal with control information. In this conventional CD, sub-codes of 8 bits such as P, Q, R, S, T, U, V and W are prepared. When text information is recorded in the conventional CD, channels of 6 bits composed of R, S, T, U, V and W are used.
2.2. First Problems to be Solved by the Invention
However, in cases where both a video signal and an audio signal are recorded in the DVD, the video signal is primarily recorded in the DVD (hereinafter, this type of DVD is called DVD-video disc), and the recording of the audio signal is subordinated to the recording of the video signal. Therefore, there are following problems.
First, the audio signal is integrally formed with the video signal, and the audio signal and the video signal are recorded as a set. Therefore, a memory capacity for the audio signal is considerably lower than that for the video signal.
Secondly, a time management for the audio signal cannot be performed independent of the video signal.
Thirdly, simple text information such as a music name cannot be read out from the DVD-video disc.
Also, because users for the audio signal require a broaden usage from the DVD-video disc as compared with users for the video signal, a simple reproducing method is required of the DVD-video disc. For example, the users for the audio signal desires to arrange an area of table-of-contents (TOC) in the DVD-video disc in the same manner as in the CD. However, in the DVD-video disc, a video contents block unit is composed of a navigation control pack (CONT pack), a plurality of video packs and a plurality of audio packs, and the reproduction of the video and audio packs is controlled by using the CONT pack. Therefore, even though the audio signal is primarily recorded in the DVD-video disc independence of the video signal, a user cannot easily reproduce the audio signal, so that there is a problem that the DVD-video disc is not very useful for the user.
Also, the time management in the DVD-video disc is performed for each video frame. Therefore, even though the audio signal is primarily recorded in the DVD-video disc independence of the video signal, because it is important to continuously reproduce the audio signal as compared with the video signal, there is a problem that it is difficult to perform a time management for the audio signal in real time.
Also, the DVD-video disc and a DVD-video disc reproducing apparatus dedicated to the DVD-video disc are put on the market. In this DVD-video disc reproducing apparatus, a signal recorded in a music CD or a video CD can be reproduced as well as a signal recorded in the DVD-video disc. However, users desire a disc reproducing apparatus in which an audio signal recorded in any type DVD can be reproduced as well as the reproduction of an audio signal primarily recorded in a DVD (hereinafter, this type of DVD is called DVD-audio disc)
2.3. Second Problems to be Solved by the Invention
Also, text information indicating contents of a music source and other information are recorded in the conventional CD by scatteringly arranging the text information and the other information in a storage region of the conventional CD. In this case, it is difficult, for example, to display the text information and the other information while the text information and the other information follow the music source reproduced and while promptly changing the text information and the other information. Therefore, there is a problem that a text indicated by a video signal cannot be effectively displayed in connection with the music source indicated by an audio signal.
In general, in cases where a dialogue (or a caption) superimposed on a moving picture such as a movie is recorded in a digital versatile disc (DVD)-video disc, text information represented by the dialogue is recorded by successively arranging the text information in a storage region of the DVD-video disc. However, because audio data such as a music source is primarily recorded in the DVD-audio disc as compared with the DVD, there is a problem that a specific storage region allocated to the audio data is considerably reduced in the DVD-audio disc in cases where text information is successively arranged in a storage region of the DVD-audio disc.